The invention is directed to avalanche semiconductor switch devices. More specifically, the invention is directed to techniques for integrating device triggers into a solid state or semiconductor device such as a BASS (Bulk Avalanche Semiconductor Switch) device or a surface avalanche semiconductor switch device.
An avalanche semiconductor switch device is generally utilized as an optically triggered switch. A typical avalanche semiconductor switch device comprises a doped semiconductor material between two electrical contacts.
An avalanche semiconductor switch device may consist of two electrodes of about one square millimeter area on each side of a one millimeter thick GaAs substrate. The avalanche semiconductor switch device generally operates as a switch which is optically triggered. When a bias voltage is applied across the electrodes or contacts, the avalanche semiconductor switch device conducts in response to an intense pulse of light. For example, if the bias voltage is above a threshold value, typically in the range of 3-5 kV, and the optical energy from the light is also above a threshold value, typically 1-2 nJ in a few nsec, the avalanche semiconductor switch device enters a state of very high conductance.
When the light is above the threshold value, photoconductors are generated in the avalanche semiconductor switch. The photoconductors cause charge carriers (i.e., electrons and holes) to collide with atoms, knocking lose electron-hole pairs, which in turn creates additional electron-hole pairs, thereby creating an exponentially increasing current level in the avalanche semiconductor switch device. This exponential increase of current flow is known as avalanche breakdown. Thus, the avalanche semiconductor switch device operates as a switch which reaches very high conductance in response to being optically injected.
Heretofore, avalanche semiconductor switch devices are generally utilized in applications which optically isolate the input and the output. However, the avalanche semiconductor switch device generally requires the use of a high power light source to provide a high power optical input (intense pulse of light) to the avalanche semiconductor switch device. The high power output is generally over 10 Watts peak power which is provided by expensive laser diodes and drivers with expensive handbuilt optical interfaces. Thus, there is a need in the art to provide an integrated device trigger for injecting charge carriers directly into the avalanche semiconductor switch device.